Various improvements have been made in color photographic light-sensitive materials since Kodachrome was first sold in 1935 utilizing Maxwell's principle of color photography and Helmholtz's three primaries. Specific improvements include improvement of the three primary coloring dyes to be used, improvement of the blue-sensitive, green-sensitive, and red-sensitive spectral sensitivities, the elimination of any unfavorable spectral characteristics from three primary coloring dyes by introduction of color-making property thereinto, and the prevention of color-mixing caused between the respective light-sensitive layers by incorporation of an appropriate DIR-compound having a interlayer effect into light-sensitive layers. However, the all-around consideration on the human visual spectral sensitivity characteristics (for example, including the human three primary color stimulative value curve, etc.) was not still given. Accordingly, any concrete means to visually express gradation of objects with high density and high chroma, and to express the difference of hue with delicate variation, could not be practically applied to color photographic light-sensitive materials, hitherto, although the theoretical mechanism of such means has been known.
For example, Japanese Patent Application (OPI) No. 18245/79 (the term "OPI" as used herein refers to a "published unexamined Japanese patent application") describes the incorporation of a DIR-coupler or a DIR-hydroquinone derivative in a blue-sensitive layer, green-sensitive layer, or red-sensitive layer in combination with another color coupler so as to improve the sharpness, color saturation, and graininess of the final images. However, no consideration is given to the details of the spectral characteristic considering human sensitivity on color in OPI No. 118245/79, and thus, the image quality of the color photograph obtained therein is not satisfactory.
U.S. Pat. No. 3,672,898 describes the relative spectral sensitivity distribution of light-sensitive layers having excellent color-renderability, especially high neutral color-renderability, in multilayer color photographic light-sensitive materials exposed to various light sources for picture-taking. However, this U.S. Patent also has no description of giving consideration to the details of human color-sensitive spectral characteristics, spectral absorption characteristics of the respective coloring dyes, masking characteristics in the interlayer between the respective three primary color layers, and self-compensating characteristics by interlayer effect. Accordingly, the color-reproduction quality of the color photographs according to this U.S. Patent is still not totally sufficient.
Japanese Patent Application (OPI) No. 34541/86 and Japanese Patent Application Nos. 42155/85 and 651/86 describe a method wherein an interlayer effect which is negative with respect to the red-sensitive layer is imparted, preferably in the wavelength range of from 500 nm to 560 nm, while the center of gravity of the wavelength (the weight-averaged wavelength) of the defined interlayer effect is on the side of a longer wavelength range than the spectral sensitivity distribution of the green-sensitive layer.
For example, Japanese Patent Application No. 39734/85 describes provision of a silver halide emulsion layer having an intermediate spectral sensitivity distribution between the spectral sensitivity distribution of a red-sensitive layer and that of a green-sensitive layer, and the incorporation of a specific DIR-compound which impart a negative interlayer effect to other layers in the emulsion layer. Despite the incorporation of such compound, the effect is still not totally sufficient.
Furthermore, there still are various other problems to be solved relating to visual spectral sensitivity characteristics of photographic materials, including the spectral characteristics of the respective three color formers incorporated, the spectral sensitivity distributions of the blue-sensitive, green-sensitive, and red-sensitive emulsion layers, and the actual color-mixing in the light-sensitive layers.
In the case of a system where three color formers, such as a cyan-dye-forming coupler, a magenta-dye-forming coupler, and a yellow-dye-forming coupler are used, it is necessary to provide a negative interlayer effect with respect to the respective emulsion layers of the color photographic light-sensitive materials in order to obtain a favorable color-reproducibility, as is apparent from FIG. 1, which shows spectral sensitometric curves for quasi-colorimetric reproduction, and in addition, it is necessary to give an effect capable of forming a cyan image to the blue-sensitive emulsion layer (BL), as noted from the curve (R) in FIG. 1.
The present inventors conducted various experiment in order to satisfy the above noted desirable properties, and succeeded in improving the color-reproducibility and also in obtaining photographs with natural color images. as is disclosed in Japanese Patent Application (OPI) No. 34541/86. Surprisingly, however, it was found that the improvement of the color-reproducibility for the formation of natural color image photographs often causes extreme drawbacks with respect to the graininess and the sharpness of the color images formed. It is of course necessary that the image sharpness and the graininess are well balanced with respect to the excellence of the light-sensitive emulsion layers, viz., the blue-sensitive emulsion layer (BL), green-sensitive emulsion layer (GL), and red-sensitive emulsion layer (RL). In this connection, it has been found that if the graininess and the image sharpness are poor, as mentioned above, the improved effect of the color-reproducibility can not be visually appreciated.